KR20080031134A - Hollow organic pigment core binder coated paper and paperboard articles and methods for making the same - Google Patents

Abstract

A paperboard product, a papermaking laminate, and a method for manufacturing the paperboard product are provided to improve gloss, brightness, and smoothness of the paperboard product. A paperboard product comprises one or more hollow-core binders of a first polymer containing one or more voids. The first polymer is substantially encapsulated by a second polymer. At least one of the first polymer and the second polymer, as polymerized unit, is formed of one or more ethylene-based unsaturated monomers. The second polymer has a glass transition temperature ranging from -15°C to 30°C. A weight ratio of the second polymer to the first polymer ranges from 1:1 to 4:1. Further, the second polymer of the hollow-core binders is formed from butyl acrylate, ethyl acrylate, ethyl hexyl acrylate and a mixture thereof.

Description

Hollow organic pigment core binder coated paper and paperboard articles and methods for making the same}

The present invention relates to a method of coating cardboard and making paper with a hollow core binder and to coated paper and cardboard products formed by such a method. More particularly, the present invention relates to a process for coating cardboard and making paper with an aqueous dispersion comprising binder coated voids comprising polymeric pigment particles having a binder having a glass transition temperature sufficient to provide a coating film, the process Provides endurance, thereby enabling high gloss cardboard coatings and making paper making and accessing cardboard coatings at low cost.

 To enable strong cardboard coatings with the desired opacity and brightness, one of ordinary skill in the art will usually use more binder and more titanium dioxide. However, excessive competition in the papermaking and cardboard coatings industry limits the amount of expensive binders and titanium dioxide that can be used. Accordingly, lower amounts of conventional binders and titanium dioxide are needed for cardboard coatings in order to recognize similar implementations as conventional cardboard coatings, thus reducing the cost of coating and paper manufacturing for paper (board) manufacturers. Do.

It is also known that the energy required for a conventional cardboard coating process is expensive, especially when a medium-gloss or high-gloss coating is desired. Synthetic resin pigments, such as solid polystyrene beads, hollow fiber and organic opaque pigments have been used to increase opacity and gloss in papermaking and cardboard coatings. However, some potential drawbacks are known in such coatings, such as reduced coating strength, increased coating and print staining, and increased cost.

Binder coated hollow sphere pigments provide binding and light scattering properties, thus simplifying the formulation of coatings and wet paper making materials. For example, US Pat. No. 6,139,961 to Blankenship et al. Discloses an aqueous dispersion of water-insoluble core / sheath polymer particles used in coated and cardboard. In the core / cover particles, the core contains one or more voids encapsulated by the first shell polymer having a glass transition temperature, T _g , above 50 ° C .; Moreover, a second shell polymer having a glass transition temperature of -15 ° C to -50 ° C is polymerized on the first shell. The second shell of core / cover polymer particles comprises at least 15% by weight of the total weight of the first shell polymer and the second shell polymer; The weight ratio of core polymer to first shell polymer is from 1: 2 to 1: 100. Dispersions such as Blankenship provide opacity for the coatings containing them. However, coatings such as Blankenship provide inadequate strength to protect the coated product from damage during processing and do not provide acceptable high gloss coatings. As a result, additional binders and opaque pigments must be used to achieve acceptable coating strength and gloss, which can be very expensive.

Applicants have made efforts to solve the problem to provide a low cost, medium gloss or high-gloss cardboard coating that can withstand the process of cardboard coating.

The method of the present invention comprises applying a coating composition to a cardboard substrate, the coating composition comprising an aqueous dispersion of one or more hollow-core binders of a first polymer containing one or more voids, wherein the first polymer comprises one or more agents Substantially encapsulated by two polymers, wherein the second polymer has a glass transition temperature (T _g ), including greater than -15 ° C. and up to 30 ° C., eg, 25 ° C. or less, and furthermore, The weight ratio of the two polymers is from 1: 1 to 4: 1 and dried and / or cured to form a coating. One or both of the first and second polymers are formed from one or more ethylenically unsaturated monomers as polymerized units. Preferably, the first polymer is a multilayered polymer formed from one or more ethylenically unsaturated monomers as polymerized units and has a void containing core layer, such as an alkali swellable or alkali hydrolyzable polymer. Preferably, the second polymer is formed as a polymerized unit from at least one ethylenically unsaturated monomer, more preferably at least one mono-ethylenically unsaturated monomer. The second polymer may also be a condensation polymer. T _g of the first polymer is at least 50 ℃, preferably more than 75 ℃. Preferably the weight ratio of the second polymer to the first polymer is 2: 1 to 3: 1.

Alternatively, the process of the present invention mixes cellulose fiber pulp with a composition comprising an aqueous dispersion of at least one hollow-core binder according to the present invention prior to or during the formation of the sheet or board of paper or cardboard, Forming a sheet or board by processing such as calender or compression, and drying to form a paper, paper laminate or cardboard product.

In the process of the invention, the composition may further comprise a binder selected from paper pulp binder and a coating binder. In addition, the compositions of the present invention may include fillers, opaque pigments such as titanium dioxide, calcium carbonate or combinations thereof.

The composition provides a pinhole free coating on the cardboard product and enables the manufacture of a substrate having a desired opacity and lightness coating. Moreover, the strength and light-scattering of the cardboard coatings and paper products made from the coating compositions of the present invention are increased compared to coatings having the same amount of binder and titanium dioxide.

In addition, the present invention provides a coated cardboard product having a coating formed thereon from the composition of the present invention. Moreover, the present invention provides paper, laminated paper or cardboard made from the composition of the present invention. In the case of laminate paper, at least one layer of the laminate comprises the hollow core binder of the present invention.

All ranges disclosed are inclusive and combinable. For example, the average particle diameter of at least 200 nanometers (nm) and at most 5000 nm, preferably at most 1500 nm, more preferably at least 300 nm, more preferably at most 1000 nm, is 200 nm to 5000 nm or 300 to 5000 nm, or 200 nm. To 1000 nm, or 300 nm to 1000 nm, or 200 nm to 1500 nm, or 300 nm to 1500 nm.

Unless otherwise indicated, all temperature and pressure units are standard temperature and pressure (STP).

All phrases involving insertion refer to the included insertion material or the absence thereof, or both. For example, the phrase "(meth) acrylate" optionally includes acrylates and methacrylates; Likewise, the phrase "(co) polymer" optionally refers to a polymer or copolymer.

Unless stated otherwise, the term “average particle size” as used herein means particle size as determined by light scattering using a BI-90 Plus instrument from Brookfield Instrument Company, Middleboro, Massachusetts.

The term "component" as used herein means a composition comprising a particular material. For example, the initiating component may simply be referred to as an initiator or may comprise an initiator pre-dispersion of an initiator, an aqueous liquid and an emulsion or a surfactant.

Unless otherwise stated, the term “glass transition temperature” or T _g as used herein is defined by the Fox formula (TG Fox, Bull . Am . Physics Soc . , Volume 1, Issue No. 3, page 123 (1956)). For copolymers comprising polymerization products of more than two different monomers, the calculation can be expressed as follows:

1 / T _g = Σ [w (Mi) / T _g , (Mi)],

Wherein w (Mi) is the weight fraction of each monomer,

T _g , (Mi) is the glass transition temperature of the Mi homopolymer. In the case of any multilayer polymer, the disclosed T _g represents the T _g measured from all monomers used to prepare the entire multilayer polymer.

As used herein, the term “experimental T _g ” refers to the amount measured via differential scanning calorimetry (DSC) at a heating rate of 20 ° C. per hour, with T _g taken at the center of the curve or peak. If "test phase T _g" is disclosed to an arbitrary multi-layer polymer, the T _g Experiment disclosed represents the T _g of the outer layer of the multi-layer polymer. Unless stated otherwise, for example, the T _g of a polymer, except for additional polymers such as condensation polymers such as polyesters, is experimentally T _g .

The term "solid high content" as used herein refers to a solids content of more than 50% by weight, preferably more than 60% by weight.

The term "(meth) acrylate" as used herein refers to acrylates, methacrylates and mixtures thereof, and the term "(meth) acryl" herein refers to acrylics, methacryl and mixtures thereof.

Unless stated otherwise, the phrase “molecular weight” as used herein refers to a weight average molecular weight as measured by gel permeation chromatography (GPC) on polyacrylic acid (PAA) standards of hydrolyzed copolymers in KOH.

The term "pigment volume concentration" or PVC, as used herein, refers to the amount determined by the following formula:

As used herein, the term “substantially encapsulated” means that the surface area of more than 50% of the encapsulated particles, eg, (co) polymers, is determined by an encapsulant such as a first polymer or a second polymer. It means to be covered.

The term "void" as used herein refers to a polymer free space, filled with air or another gas, when the material containing it is dried.

The term “volatile organic compound” or (VOC) as used herein is defined as a carbon-containing compound having a boiling point of less than 280 ° C. at atmospheric pressure.

As used herein, the term “wet-end” or “wet-end treatment” refers to the portion of paper or paperboard processing in which, on the paper machine, remarkably the cellulose fiber pulp slurry is formed into a wet sheet by techniques known in the art. To mention.

As used herein, the phrase “% by weight” means percent by weight.

In the hollow core binder of the present invention, upon drying, the first polymer comprises at least one void having a diameter of at least 50 nm, or at most 1500 nm, preferably at least 100 nm and preferably at most 700 nm, and the second polymer Substantially encapsulates the first polymer. Coatings and papermaking compositions with hollow core binders of the present invention have up to 30% by weight of each expensive opaque pigment, such as titanium dioxide, which have strength and opacity properties comparable to coatings with binder polymer added thereto. To provide a coating and papermaking product. Moreover, hollow core binder compositions more easily form films and require less energy than comparable gloss and quality coatings, thus having economical, high quality cardboard coatings and paper products, especially medium-gloss or high gloss. Makes its provision possible.

The composition of the first polymer and the second polymer is selected to provide durability in the treatment and to enable formation of a coating having the desired appearance properties. Each of the first polymer and the second polymer of the hollow core binder may comprise a polymerized product of one or more ethylenically unsaturated monomers, preferably one or more mono-ethylenically unsaturated monomers. Moreover, each of the first polymer and the second polymer of the hollow core binder may independently comprise a multilayer copolymer having two or more layers. The first polymer may be a condensation polymer such as polyester, polyurethane, polyamide or alkyd. The second polymer may comprise various binder compositions such as styrene-butadiene copolymers. The T _g of the first polymer is at least 50 ° C. and may be up to 150 ° C. Preferably, the T _g of the first polymer is at least 75 ° C, or more preferably at least 80 ° C. The T _g of the second polymer is greater than -15 ° C and up to 30 ° C, for example at most 25 ° C, preferably at least -5 ° C. Preferably the T _g of the second polymer may be at most 10 ° C, more preferably at most 5 ° C.

Preferably, the first polymer comprises any one or more (co) polymers as core polymer or layer polymerized unit and comprises a multilayer copolymer having a core, wherein the one or more voids are alkali swell, alkali hydrolysis By known methods, including by the removal of leaving substances or removable porogens therefrom, by the use of swelling agents activated after polymerization, or by the use of solvents to dissolve the void portion It can be formed from a polymer. Optionally, the first polymer may comprise a single layer polymer in which the inner void or hollow space can be formed by using an swelling agent to create the inner void by removing the encapsulated leaving material or removable progeny from it. Accordingly, the core of the multilayer first polymer may comprise any swellable polymer, such as a solvent soluble polymer, such as an alkali swellable polymer or a polymer soluble in water or an organic solvent; Accordingly, any core of a single layer first polymer or multi-layer first polymer may contain a leaving, porogen or swelling agent to form one or more voids.

Alkali swellable polymers are polymerized units, for example, at least one mono- hydrolyzable and swellable in an alkaline environment at temperatures above the polymer T _g such as (meth) acrylate esters, vinyl esters of carboxylic acids or mixtures thereof. Ethylenically unsaturated acids or one or more acid free polymer units.

Organic solvent soluble polymers and the solvents in which they are dissolved are disclosed, for example, in US Pat. No. 5,989,630. Suitable organic soluble polymers include, as polymerized units, 1 to 20 carbon alkyl (meth) acrylates, aromatic vinyl compounds, vinyl esters of carboxylic acids having 1-20 carbon atoms, mono (meth) acrylates of alkanediols, ( Meth) acrylamide, vinyl ethers of 1-20 carbon alkanols, diesters of 1-20 carbon alkanol (meth) acrylonitrile and ethylenically unsaturated dicarboxylic acids, vinyl halides and (di) olefins can do. Suitable solvents may include toluene, or mixtures of solvents (coagulants) that are good for the subject polymer, such as, for example, toluene, for example very bad for the polymer, such as n-octane; Particularly advantageous is a mixture of toluene and n-octane, and good results are obtained when the toluene to n-octane ratio is in the range of about 5: 1 to about 1: 1.

The first polymer may comprise, as polymerized units, at least 50% by weight of nonionic mono-ethylenically unsaturated monomers, and optionally at least one copolymerized mono-ethylenically unsaturated monomers. Such first polymer may be formed by free radical polymerization. The first polymer may also be a condensation polymer such as, for example, polyester, polyurethane or polyamide.

The first polymer is a polymerized unit, based on the total weight of the monomers used to make the polymer, from 0.05 to 50% by weight, preferably at least 0.2% by weight, preferably at most 35% by weight, more preferably from 0.5 to 25 weight percent, even more preferably 1 to 5 weight percent of the multi-ethylenically unsaturated monomer.

Preferably, the core layer of the multilayer first polymer is a polymer unit, wherein from 5 to 100% by weight of at least one hydrophilic mono-ethylenically unsaturated monomer, preferably (meth) acrylic acid and the core polymer, based on the weight of the core layer polymer By weight, from 0 to 95 weight percent of at least one nonionic mono-ethylenically unsaturated monomer. Such core layer polymers may be alkali swellable acid-group containing or alkali hydrolyzable polymers.

The second polymer can be any polymer having the desired T _g , including but not limited to addition (co) polymers and condensation (co) polymers. If the second polymer is a condensation polymer, it may be incorporated into a condensation reactive group in the first polymer. For example, if the first polymer comprises an amine or hydroxyl group, the second polymer may be a urethane polymer, an alkyd or a carboxyl functional polyester; Likewise, if the first polymer comprises acid groups, the second polymer may comprise polyester polyols, polyurethane polyols or hydroxyl functional polyesters.

Each of the first polymer and the second polymer is a polymerized unit, based on the total weight of monomers used to prepare the polymer, from 0% to 7.5% by weight, preferably 0% to 2.5% by weight of at least one mono It may contain independently an ethylenically-unsaturated acid or diacid monomer, or anhydride thereof.

As the polymer unit, both the acid monomer and the amide monomer can be introduced into the second polymer, such as 0.1 to 2.5 wt% acrylic acid and 1 to 2.5 wt% acrylamide, based on the total weight of the monomers used to make the polymer. have.

Suitable mono-ethylenically unsaturated monomers for the first polymer and / or the second polymer are, for example, C ₁ to C ₃₀ (cyclo) alkyl (meth) acrylates, for example methyl (meth) acrylate, ethyl Methacrylate, butyl acrylate, 2-ethylhexyl (meth) acrylate, decyl acrylate, lauryl (meth) acrylate, isodecyl (meth) acrylate, hydroxyalkyl (meth) acrylate, acetoacetoxy Amine-functional such as ethyl (meth) acrylate, acetoacetoxyalkyl (meth) acrylate, 2- (3-oxazolidinyl) ethyl (meth) acrylate and tert-butylaminoethyl (meth) acrylate (Meth) acrylic ester monomers, including; (Meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide; (Meth) acrylonitrile; Ethyleneureido-functional monomers; Allyl acetoacetate; Ethylene; Propylene; Styrene and substituted styrenes; butadiene; Vinyl esters such as vinyl acetate and vinyl butyrate; Vinyl imidazole, vinyl chloride, vinyl toluene and vinyl benzophenone; And vinylidene chloride. Preferably, the first polymer and the second polymer are mainly formed from (meth) acryl, styrene / (meth) acrylic or vinyl acetate / acrylic monomers; More preferably, the first polymer is formed from styrene or all (meth) acrylic monomers. The second polymer is preferably formed from butyl acrylate, ethyl acrylate, ethyl hexyl acrylate and mixtures thereof.

Suitable mono-ethylenically unsaturated acids or diacid monomers are, for example, (meth) acrylic acid, itaconic acid; Fumaric acid; Maleic acid; Monoalkyl itaconate; Monoalkyl fumarate; Maleic anhydride; 2-acrylamido-2-methylpropane sulfonic acid; Vinyl sulfonic acid; Styrene sulfonic acid; 1-allyloxy-2-hydroxypropane sulfonic acid; Alkyl allyl sulfosuccinic acid; Sulfoethyl (meth) acrylate; Phosphoalkyl (meth) acrylates such as phosphoethyl (meth) acrylate; Phosphodialkyl (meth) acrylates; And allyl phosphate. Preferred acid monomers are (meth) acrylic acid, itaconic acid, fumaric acid and maleic acid.

 Suitable hydrophilic mono-ethylenically unsaturated monomers useful for preparing the core polymers include acrylic acid, methacrylic acid, acrylicoxypropionic acid, (meth) acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid or anhydride, fumaric acid, crotonic acid. Monomers containing acid-functionality, such as carboxylic acid groups, including monomethyl maleate, monomethyl fumarate and monomethyl itaconate; And monomers comprising hydroxyl or amine groups. Acrylic acid and methacrylic acid are preferred.

Suitable multi-ethylenically unsaturated monomers include allyl methacrylate, diallyl phthalate, for example glycol di (meth) acrylates such as 1,2-ethyleneglycol dimethacrylate; Such as divinyl benzene, for example, those having two or more ethylenically unsaturated bonds.

The hollow core binder of the present invention can be formed by various processes known in the art to form an aqueous dispersion of the first polymer and to form a second polymer shell that substantially encapsulates the first polymer. The second polymer is polymerized in the presence of the first polymer.

Each of the first polymer and the second polymer aqueous emulsion polymer can be prepared by known polymerization techniques; Accordingly, the hollow core binder of the present invention can be formed by emulsion polymerization. For example, the hollow core binder is the first polymer, which emulsion-polymerizes the core-shell copolymer, adds the polymerized core-shell copolymer to the aqueous emulsion, and at least one mono-ethylenically unsaturated in the presence of the core-shell polymer. The polymer may be formed by polymerizing the monomer to form a second polymer and further adding a swelling agent to the aqueous dispersion before, during or after the polymerization of the mono-ethylenically unsaturated monomer of the second polymer. The second polymer may be formed in the same reaction tube or bath tube as the first polymer. Optionally, the second polymer may be formed after a period of time in another reaction tube or bath tube, such as a holding tank, a drain tank. The polymerization temperature of the second polymer will be at least 30 ° C. below the measured T _g of the first polymer. Preferably, the process comprises polymerization of at least 10% of the mono-ethylenically unsaturated monomers of the second polymer at temperatures of 5 ° C to 65 ° C.

The first polymer and the second polymer each independently comprise a polymer or multilayer polymer with multiple phases, each phase comprising at least one copolymerized mono-ethylenically unsaturated monomer, each having a desired T _g . Preferably, each of the first polymer and the second polymer is formed by multilayer polymerization, and the second polymer is formed in the presence of the first polymer.

In a more preferred embodiment, at least 10, preferably 20, more preferably 50 and most preferably 100% by weight of the entire second polymer is from 5 ° C to 65 ° C, preferably from 10 ° C to 50 ° C, more preferably 20 ° C. Formed by polymerization at a temperature of from 40 ° C., wherein the polymerization temperature is at least 30 ° C. below the T _g of the first polymer. The temperature at which the second polymer is formed is allowed to exceed 65 ° C. during the formation of the second polymer, provided that at least 10% of the second polymer is formed at a temperature between 5 ° C. and 65 ° C., wherein the polymerization temperature is at At least 30 ° C. lower than the T _g of one polymer.

In another preferred embodiment, the concentration of unpolymerized monomer in the reaction tube is 6% by weight or less at any time (T), preferably, based on the total weight of the reaction mixture present in the reaction tube at time (T). 5 wt% or less, more preferably 4 wt% or less.

Each of the first polymer and the second polymer may be prepared by independently selecting a surfactant, an initiator, and other additives, for example, they may be the same or different in kind and amount from each polymer. In any emulsion polymerization process, for example, alkali metal or ammonium salts of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates; Alkyl sulfonic acid; Sulfosuccinate salts; fatty acid; Ethylenically unsaturated surfactant monomers; And conventional surfactants such as, for example, anionic and / or nonionic emulsions, such as ethoxylate alcohols or phenols. The amount of surfactant can be used from 0.1% to 6% by weight, based on the total weight of monomers used to form any polymer.

The first polymer and the second polymer can be polymerized independently, for example, via free radical polymerization including heat, redox reactions, photochemical action and electrochemical initiation. When the reaction temperature is maintained at 5 ° C to 65 ° C while at least 10% by weight of the second polymer is formed, the redox reaction polymerization step is preferably performed in between.

In any polymerization any monomer may be added neat, for example as a non-emulsion in water or as an oil in water. The monomers may be added over one or more additions or continuously, continuously or discontinuously, or in any combination thereof. In the case of polyesters or polyamides, the reactive polyacids and polyols (or polyamines) can be polymerized in large quantities in the presence of known condensation catalysts such as trialkyl tin oxides.

Each of the first polymer and the second polymer may be independently formed using a suitable free radical initiator (oxidant) or a redox catalyst. Suitable initiators include, for example, persulfates such as ammonium and / or alkali metal persulfates; Peroxides such as, for example, sodium or potassium hydroperoxide, t-butyl hydroperoxide, t-alkyl hydroperoxide, dicumyl hydroperoxide; t-alkyl peroxide or t-alkyl perester, wherein the t-alkyl group comprises at least 5 carbon atoms; Perborate and salts thereof, such as, for example, sodium perborate; Superphosphate and salts thereof; Potassium permanganate; And ammonium or alkali metal salts of peroxydisulfonic acid. Such initiators may be used in amounts ranging from 0.01% to 3.0% by weight, based on the total weight of the monomers. Redox catalysts comprising one or more oxidants in combination with suitable reducing agents include, for example, sodium sulfoxylate formaldehyde; Asocorbic acid; Isoascorbic acid; Alkali metal and ammonium salts of sulfur-containing acids such as sodium sulfite, bisulfite, thiosulfite, hydrosulfite, sulfide, hydrosulfide or dithionite; Form adine sulfinic acid; Hydroxymethanesulfonic acid; Sodium 2-hydroxy-2-sulfinatoacetic acid; Acetone bisulfite; Amines such as ethanolamine, glycolic acid; Glyoxylic acid hydrate; Lactic acid; Glyceric acid; Malic acid; Tartaric acid; And salts of the acids may be used in amounts of 0.01% to 5.0% by weight based on the total weight of the monomers.

Redox catalytic metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium or cobalt may be added to form the first polymer and the second polymer. Typical levels of catalytic metal salts used in accordance with the present invention are from 0.01 ppm to 25 ppm and can be up to 1.0% by weight, based on the total weight of the monomers. Mixtures of two or more catalytic metal salts may also be usefully employed. Chelated ligands that can be used with catalytic metal salts include, for example, nitrilotriacetic acid (NTA, tetradentate ligand), ethylene diamine diacetic acid (EDDA, tetradentate ligand), N- (hydroxyethyl) ethylene diamine tri Multidentate aminocarboxylate ligands such as acetic acid (HEDTA, 5-dentate ligand) and ethylene diamine tetraacetic acid (EDTA, 6-dentate ligand).

Mercaptans such as alkyl thioglycolate, alkyl mercaptoalkanoates and C ₄ -C ₂₂ linear or branched alkyl mercaptans; Halogen compounds including tetrabromomethane; Or a chain transfer agent such as mercaptocarboxylic acid can be used to control the molecular weight of the first polymer and the second polymer. The chain transfer agent may be added over most or all of the entire reaction period, or for one or more additions or continuously, continuously or discontinuously, for a limited portion of the reaction period. Suitable amounts of chain transfer agent are 0.25% to 10% by weight, based on the total weight of the monomers.

The first polymer and the second polymer may independently comprise a single layer polymer, or may contain a plurality of phases, for example as formed by multilayer emulsion polymerization. Multilayer emulsion polymerization results in the formation of at least two mutually incompatible polymer compositions and the formation of at least two phases in the polymer particles. Such particles are, for example, core / shell or core / cover particles, core / shell particles with a shell phase partially encapsulated in the core particles, core / shell particles with multiplicity of cores, interpenetrating network particles, for example. It consists of two or more phases with The multilayer emulsion copolymer can be formed from two or more layers of different molecular weights as well as the composition.

Preferably, the aqueous dispersion of the present invention provides an aqueous dispersion of a multilayer emulsion polymer comprising a core layer polymer ("core") and a first shell layer polymer ("first shell"), The addition of at least one mono-ethylenically unsaturated monomer forms a second shell layer polymer (“second shell”) that substantially encapsulates the first shell polymer and, in the presence of the multilayer polymer, calculates the first shell layer polymer At least 10% of the monomers are polymerized at a temperature of 5 ° C. to 65 ° C. at least 30 ° C. below the Tg. The core of the multilayer emulsion polymer is swelled by adding a swelling agent to the aqueous dispersion before, during or after the polymerization of the monomer comprising the second shell layer polymer. Such a preferred process is as disclosed in US Patent Publication No. 20010009929A.

Whether obtained by a single layer process or by a process comprising several layers, the core layer of the first polymer under non-swelling environment has an average particle of 50 nm to 1.0 micron, and preferably 100 nm to 300 nm. Has a size diameter. As disclosed in US Patent No. 20010009929, if the core is obtained from a seed polymer, the seed polymer preferably has an average particle size of 30 nm to 200 nm. The core may also contain less than 20% by weight, preferably 0.1 to 3% by weight, of multi-ethylenically unsaturated monomers, based on the total weight of the core.

The core and shell of the preferred first polymer may consist of multiple layers. There may also be one or more mediation layers. Preferably, the multilayer polymer comprises a core, an intervening layer and a shell. An arbitration layer is disclosed in US Patent No. 20010009929A.

The hollow core binder particles of the present invention comprise a first polymer and a second polymer that substantially encapsulates the first polymer. Preferably, more than 75%, more preferably 100% of the surface area of the first polymer particles are covered by the second polymer. Encapsulation or cover range of the polymer particles can be determined by scanning electron microscopy, with or without staining techniques, as known in the art.

The hollow core binder particles of the invention have an average particle diameter of at least 200 nanometers (nm), at most 5000 nm, preferably at most 1500 nm, more preferably at least 300 nm, or more preferably at most 1000 nm. Also contemplated are multi-site, eg, 2- or multi-site, particle size emulsion polymers.

Upon drying, the first polymer comprises at least one void. Preferably, the void size may range from at least 50 nm, preferably at least 100 nm, at most 1200 nm, preferably at most 800 nm. In some embodiments in which the particles of the present invention increase the opacity of the film in which they are present, it is preferred that the void size ranges from 200 to 700 nm.

Single void containing polymers are formed by multilayer emulsion polymerization, and their preparation methods are described in US Pat. No. 4,427,836; No. 4,469,825; 4,594,363; No. 4,970,241; No. 5,225,279; 5,494,971; 5,494,971; 5,510,422; 5,510,422; No. 5,527,613; No. 6,020,435; 6,139,961; 6,139,961; No. 6,673,451; And 6,784,262, as well as US Patent Publication No. 20010009929A; 20010036990A; And known in the art as disclosed in 20030129435A.

Upon drying, suitable first polymers are also separated or connected to other voids, whether the structure is substantially spherical, for example interpenetrating networks of void channels, voids and polymers, for example US Pat. No. 5,036,109 number; 5,216,044; It may contain two or more voids comprising a sponge-like structure as disclosed in 5,521,253 and 5,989,630. Multiple voids may be formed in the core polymer particles, wholly or partially wrapped by the first polymer, or in the inner layer of the multilayer first polymer.

The voids may be formed by swelling the portion of the first polymer or multilayer first polymer particles, or by dissolving the layer or portion of the first polymer particles, for example, through a solvent to form voids upon drying. Optionally, the first polymer can be, for example, removable porogens such as titanium dioxide and silicon oxide, which can be removed with an aqueous acid; Leaving materials such as, for example, supercritical carbon dioxide; Or oxidizable compounds that leave voids upon oxidation.

In one embodiment, the first polymer having at least one void can be formed according to a method as disclosed in US Pat. No. 6,632,531, wherein the first polymer of the present invention comprises at least one leaving material, For example, it is formed in the presence of any material having a normal boiling point of less than 30 ° C., and the second polymer of the present invention is polymerized in the presence of the first polymer. In such embodiments, the second polymer may be formed before or after removal of the leaving material.

Preferably, suitable leaving materials include supercritical carbon dioxide, 2,2-dimethylpropane, dichlorofluoromethane, 1,2-dichlorotetrafluoroethane, butane, 1.1,2,2-tetrafluoroethane, 1, 1,1,2-tetrafluoroethane, dimethyl ether, 1,1-difluoroethane, octafluoropropane, chlorodifluoromethane, propane, pentafluoroethane, difluoromethane, sulfur hexafluoride , Hexafluoroethane, carbon dioxide, chlorotrifluoromethane, trifluoromethane, ethane, tetrafluoromethane, methane, difluoromethane, hexafluoroethane, chlorotrifluoromethane, trifluoromethane , Ethane, tetrafluoromethane, methane and combinations thereof.

Preferably, one or more swelling agents may be used to form one or more voids in the first polymer. Suitable swelling agents include those capable of penetrating the first polymer shell and swelling the core in the presence of the core-shell first polymer emulsion and monomer (s) used to form the second polymer. The swelling agent can be an aqueous or gaseous volatile or fixed base, or any combination.

Suitable wetting agents include ammonia, volatile bases such as ammonia hydroxide, volatile lower aliphatic amines such as morpholine, trimethylamine and triethylamine; Fixed or permanent bases such as potassium hydroxide, lithium hydroxide, zinc ammonium complex, copper ammonium complex, silver ammonium complex, strontium hydroxide and barium hydroxide. For example, ethanol, hexanol, octanol, Texanol® solvents and solvents such as those disclosed in US Pat. No. 4,594,363 can be added for fixed or permanent base penetration. Ammonia and ammonia hydroxides are preferred.

Preferred multilayer first polymer cores may cause swelling by adding one or more swelling agents to the aqueous dispersion before, during or after the polymerization of the monomer comprising the second shell layer polymer, but after formation of the first shell polymer. Can be. Preferably, in an environment substantially free of polymerization of monomers, the aqueous dispersion comprises at least 0.5% by weight of unreacted monomers, based on the total weight of polymer in the dispersion; When reducing the substantial value of the monomer by at least 50%, a swelling agent is added to the aqueous dispersion. The phrase "under an environment substantially free of polymerization of monomers" and techniques for achieving such an environment are as disclosed in US Patent Publication No. 20010009929A.

Preferably, the amount of swelling agent is in the range of 75 to 300%, more preferably in the range of 90 to 250%, based on the equivalent weight of functionality in the core that can be neutralized. It is further preferred to add one or more swelling agents to the multilayer emulsion polymer while the multilayer emulsion polymer is at an elevated temperature, preferably within 10 ° C. of the shell polymerization temperature. For example, substantial polymerization does not occur, and swelling, such as swelling, is generally very effective at minimal amounts of time in an elevated temperature environment in the presence of monomers. Under these circumstances, swelling is generally completed within 30 minutes, preferably within 20 minutes, most preferably within 10 minutes of the addition of one or more swelling agents.

In the presence of the monomer used to form the second polymer, after swelling of the preferred multilayer emulsion first polymer and the swelling agent, reducing the level of the monomer to less than 10,000 ppm, preferably less than 5,000 rpm, based on the polymer solids, desirable. This can be accomplished by any suitable means. Preferably, the level of monomer is reduced by the polymerization of the monomer. This may be accomplished by any suitable means, such as by adding one or more initiators disclosed above. It is desirable to begin reducing monomer levels within 20 minutes, more preferably within 10 minutes after the addition of one or more swelling agents.

In one embodiment, the first polymer comprises an organic solvent soluble polymer as the core layer or as the entire first polymer, and the voids are, as polymerized units, from 5 to 100% by weight of hydrophilic mono in a water immiscible solvent or solvent mixture. Solution polymerization of a polymer comprising an ethylenically unsaturated monomer or a first polymer, another polymer comprising a hydrophilic mono-ethylenically unsaturated monomer and a reactant for producing the first polymer as polymerized units in the resulting polymerization solution The following solution polymerization, distilling off the organic solvent at a concentration of less than 5% by weight, based on the amount of the dispersion comprising dispersing the solution comprising the first polymer and the second polymer in water in the presence of a base and substituting the solvent for water. Can be formed by The second polymer can then be emulsion polymerized to produce the hollow core binder of the present invention in the presence of an aqueous dispersion, and then the dispersion is dried. The dry dispersion can be re-dispersed in water in the presence of a base, for example ammonia. Suitable solvents include aromatic hydrocarbons such as toluene; Aliphatic hydrocarbons such as n-hexane, n-octane; Or cycloaliphatic hydrocarbons.

In embodiments wherein the first polymer comprises an alkali hydrolyzable core or inner layer, the voids may be added to an aqueous dispersion of the first polymer in a strong alkaline solution such as sodium hydroxide, in a core or inner layer such as methyl acrylate More readily hydrolyzable acrylate esters and shell layers can be formed by exposing to base amounts of about 0.75 to about 1.5 equivalents based on all acids. Expansion of the hollow latex will occur at 100 ° C to 150 ° C, preferably 110 to 140 ° C. When the crosslinking density of the shell is greater, the temperature of the expansion step will also be greater. The solvent may be aimed for swelling in the expansion step. The expansion step is about 0.5 to about 10 hours; Preferably from about 2 to about 5 hours.

The aqueous dispersion of hollow core binder particles may have more than 30 wt% solids, preferably more than 40 wt% solids. The addition of polymer particles having a smaller particle size than hollow core binder particles can produce dispersions with solid components up to 70% or more. The presence of high solids or smaller particles or a combination of both can prevent the settling or precipitation of the present invention.

The present invention provides an aqueous coating composition suitable for use as a coating of cardboard upon drying, wherein the coating composition is a hollow core binder, a binder such as styrene butadiene (S / B) latex, titanium dioxide or opaque pigments and other Pigments or fillers, for example clays. In the relatively low PVC coating form, the hollow core binder forms a continuous film impregnated with other components, including pigments and extenders. In the relatively high PVC coating form, the hollow core binder reduces the amount of opaque agent or binder needed to achieve the desired opacity or film strength. Accordingly, the pigmented coating form comprising the polymer particles of the present invention as a binder provides the same opacity, brightness and strength as the form comprising a higher proportion of non-void polymer particles and a higher proportion of opaque agent as a binder. . Accordingly, coating forms using the hollow core binder of the present invention by using lower levels of pigments and / or extenders than necessary to achieve the same level of opacity in comparable forms with non-void polymer particles as binders. The desired level of opacity can be achieved at. Moreover, hollow core binders can be advantageously used in papermaking.

The coating composition of the present invention may contain from 2 to 22% by weight, preferably 3 to 7% by weight of the hollow core binder, based on the dry weight of the pigment in the cardboard coating.

Suitable binders used in cardboard coatings are in the form of dispersions or solutions in water such as, for example, starch, hydroxyethylate starch, protein, polyvinyl acetate, poly (styrene / acrylate) and poly (styrene / butdiene). Natural or synthetic polymers. The binder particles have a film-forming property at the temperature at which the form dries. Optionally, a solvent or precipitant can be added to the softened binder particles, causing them to film-form. The binder portion is reduced relative to conventional coating compositions and, based on the weight of the dry pigment, 1.4 to 20% by weight, preferably at least 7% by weight, at most 15% by weight, more preferably 10% by weight and at maximum Can be used at a total level of 14% by weight.

Generally, the aqueous coating composition is based on the total weight of the polymer used, up to 75% by weight, preferably 5 to 50, of one or more emulsion polymer binders that do not contain an emulsion polymer non-film former, such as voids or matting agents. Wt%, more preferably 5 to 35 wt%.

Aqueous coating compositions include, for example, tackifiers, pigments, extenders, emulsions, crosslinkers, precipitating agents, buffers, neutralizers, thickeners or rheology modifiers, humectants, wetting agents, biocides, plasticizers, antifoams, colorants, And conventional coating additives such as waxes and anti-oxidants. Unless otherwise indicated, such additives may be used in conventional amounts.

Examples of suitable pigments and extenders for use in the form of coatings include clays and / or calcium carbonates such as kaolin and talaminate clays, but other inorganic or organic pigments such as lime clay, anatase and rutile Titanium oxides such as titanium oxide, calcium carbonate, and solid polystyrene particles, and hollow plastic pigments may also be included. The total amount of pigments and extenders in the aqueous coating composition varies, but can range from 60-90% by weight, preferably 65-80% by weight, more preferably 65-75% by weight, based on the total solids of the composition. . As part of the total pigment is utilized, opacifier-gloss additives such as titanium oxide, or hollow plastic pigments, and / or gloss additives, such as solid polystyrene particles, are reduced compared to conventional coating compositions, based on the total solids of the composition. 7 to 30% by weight, preferably 12 to 28% by weight, more preferably 15 to 25% by weight. In bleached cardboard coatings, an opaque agent does not need to be used.

Preferably, the aqueous coating composition comprises less than 5 wt% VOC, more preferably less than 3 wt% VOC, even more preferably less than 1.7 wt% VOC, all wt% based on the total weight of the aqueous coating composition. The coating formulation may comprise VOC in the aqueous dispersion of polymer particles, biocides, antifoams, soaps, dispersions, and thickeners, each preferably 0.1 weight based on the total weight of the aqueous coating composition. Calculated as% VOC. For example, additional methods such as steam stripping of aqueous dispersions of polymer particles and the selection of low VOCs containing additives such as biocides, antifoaming agents, soaps, dispersions and sealers can be attributed to the total weight of the aqueous coating composition. It can be used to further reduce the paint or coating with a VOC of less than 0.01 weight percent based.

Aqueous cardboard coating compositions can be prepared by techniques known in the coating art and are generally prepared by simply mixing the components. For example, to prepare a pigmented aqueous coating composition, the pigment may be dispersed in an aqueous medium under a high share, such as a COWLES® mixer, and then, under lower share stirring with other coating additives, as desired, Can be dispersed in an aqueous medium. Optionally, an aqueous dispersion of polymer particles can be included in the pigment dispersion step. The viscosity of the coating composition may range from 1000 centipoises to 5000 centipoises as measured using a Brookfield viscometer (Model LVT with spindle # 3 at 12 rpm and 25 ° C.); Viscosities suitable for other application methods vary widely and are known in the art.

The solids content of the aqueous coating composition may be 30% to 70% by weight, preferably 40 to 52% by weight, more preferably 42 to 46% by weight.

Suitable materials are, for example, recycled and unbleached cardboard and bleached cardboard, decorative laminate paper and wet-end paper pulp or wet-end paper sheets, natural cellulose formed from them, recycled or synthetic fiber pulp or It includes a sheet. In the case of bleached cardboard, the use of an opaque agent is not necessary and, based on the total solids of the composition, the binder amount is in the range of 10 to 20% by weight. The phrase "paper lamination" means paper making comprising two or more paper layers or laminas.

Coated cardboard is cardboard with an aqueous coating applied to one or two sides. Uncoated or cardboard substrates typically have a basis weight of 20-350 g / m 2, and each base coating, middle coating and / or using an effective coating method such as, for example, trailing blade coaters, size presses and air knife coaters. Multiple coatings, such as one or more of the top coatings, may be applied in amounts of 4-30 g / m 2 per side. To solve the coating replacement problem associated with the cardboard substrate, a coating can be made on the polyester film to achieve the desired coating thickness using Meyer Rod.

In another embodiment, a method for improving the strength and opacity of a papermaking or cardboard is combined with, for example, a wet sheet, before, during, or during the formation of a sheet or board from fibers, such as by pressing or calendering. As well as combining the aqueous coating composition of the invention with the paper-forming mixture at the wet end.

In another embodiment, while forming the wet-end of the paper laminate, such as decorative laminate paper, the composition comprising the hollow core binder polymer and at least one pigment is (i) an aqueous fiber in an amount useful to make a cardboard coating. The cardboard coating is combined with the pulp slurry and then formed with a wet layer of sheets or boards containing a hollow core binder, or (ii) optionally, one or more laminate layers or wet sheets or boards formed from an aqueous fiber pulp slurry. Applied in amounts useful for making. In the presence or absence of a hollow core binder, one or more additional wet layers, sheets or boards of paper are formed. The wet papermaking layers are then calendered or pressed together to form a laminate and then dried. The dried laminate is then saturated at least partially, and preferably completely with the crosslinking resin. Pressure and heat are applied to the crosslinking-resin-saturated laminate paper, causing the resin to harden and harden, forming a laminate or decorative laminate. Any suitable pigment may be used in the hollow core binder composition, but titanium dioxide is preferred. Suitable crosslinking resins include, for example, thermosetting resins including aminoplasts and phenoplasts such as formaldehyde and melamine formaldehyde and the like. Laminated paper can be heated in the range of 100 ° C to 300 ° C, preferably 125 ° C to 250 ° C, more preferably 140 ° C to 200 ° C, to cure the crosslinking resin. In addition to improved opacity, the resulting paper laminates can be obtained from decorative laminates made using only one pigment, which has a lower cost than when expensive pigments such as titanium dioxide are used. In addition, the decorative laminate paper can be formed and coated with a composition comprising a hollow core binder and at least one pigment, both before or after paper drying.

The aqueous composition coated on any substrate may be dried at a temperature of 5 ° C. to 95 ° C., or allowed to dry.

The composition provides a pinhole free coating on the cardboard product and enables the manufacture of a substrate having a desired opacity and lightness coating. Moreover, the strength and light-scattering of the cardboard coatings and paper products produced with the coating compositions of the present invention are increased compared to coatings having the same amount of binder and titanium dioxide.

The following examples illustrate the invention. In embodiments, the following abbreviations are used:

BA is butyl acrylate;

MMA is methyl methacrylate;

MAA is methacrylic acid;

t-BHP is t-butyl hydroperoxide (70%);

SDS is sodium dodecylbenzenesulfonate (23%);

DI is deionized;

SPS is sodium persulfate;

ALMA is allyl methacrylate;

L is liter; wt is weight; vol is volume; g is gram; min is minutes.

Experiment method

Kubelka Munk scattering constant (S / Mil ) decision:

The aqueous dispersion was drawn out on a black vinyl scrub chart to form a wet film, which was dried at 30% relative humidity. P.B. Mitton A.E. S was determined on a dry film (˜2 mil or ˜50 micron thick) by the method of Jacobson (Off. Digest, Sept. 1963, p. 871-911). Scattering constants per unit thickness (S / μm and S / mil) were determined using a Y-reflectometer with 45/0 geometry. The Y- reflectometer measures the Y component on the XYZ color scale and is a light reflectance meter; The 45/0 geometry indicates that the light from the top has an angle of incidence of 45 degrees with respect to the coating and the scattered light is collected at 0 degrees from the top.

Particle size: Matec CHDF-2000 (Capillary hydrodynamic fractionation); It was measured by CHDF using Metec Applied Science, Northborough, MA and A BI-90 particle size analyzer, Brookhaven Instrument Corp. (Holtsville, NY).

Gloss or sheet gloss, unless otherwise noted, was measured at 75 ° using a Technidyne T480 glossmeter (Technidyne, New Albany, IN). An experimental method for measuring gloss is TAPPI test method T-480 of the Tappi Test Methods by Tappi Press (Atlanta, GA), 1994-1995.

Brightness was measured using Technidyne Brightness Model S4-M (Technidyne, New Albany, IN). An experimental method for measuring brightness was Tappi Test Method T-452 published in Tappi Test Method by Tappi Press (Atlanta, GA), 1994-1995.

PPS smoothness was measured by a parker Print-Surf roughness tester (Model No., ME-90) manufactured by Messmer Buchel, Inc. (Kent, United Kingdom).

IGT peaks were measured at room temperature using an IGT A2 printer (IGT / Reprotest, The Netherlands) using the following standard settings: # 3 obtained from Spring B, 50 kgf (in kg) and Sun Chemicals (Menomonee Falls, WI). 4 or 5 tack black offset ink.

In Example 1 below, the polymer cores used in the preparation of the hollow core binder consisted of 66 MMA / 34MAA weight percent polymer cores prepared via aqueous emulsion polymerization according to US Pat. No. 6,020,435. The polymer core polymerization product was filtered to obtain a filtered dispersion having 31.5 wt% solids component of an average particle size of 139 nm.

Example  One: Non-swelling  First Polymer  Produce

A 5 L four-necked round flask was equipped with paddle stirrer, thermometer, nitrogen inlet and reflux condensation condensation. 950 g DI water was added to the water tube and heated to 89 ° C. under a nitrogen atmosphere. 6.0 g of sodium persulfate dissolved in 30 g of DI water was added to the heated bath tube water. Then immediately added 397 g of polymer core. The monomer emulsion (ME I) prepared by mixing 125 g DI water, 8.3 g SDS (sodium dodecyl benzene sulfonate, 23%), 125.0 g styrene, 110.0 g MMA and 15.0 g MAA was prepared at 78 ° C. It was added to the teapot over 60 minutes at temperature. After addition of ME I, the second monomer emulsion (ME II) was added 500 g DI water, 22.5 g SDS (23%), 1462.5 g styrene, 22.5 g methacrylic acid, 7.5 g flaxseed oil fatty acid (LOFA) And 18.8 g of divinyl benzene (80% activity) were mixed. Monomer emulsion II (ME II) was added to the kettle over 60 minutes with a separate mixture of 1.6 g sodium persulfate dissolved in 90 g DI water. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion between ME II and the cofeed, the reaction mixture was left at 85 ° C. for 30 minutes, then cooled to room temperature and filtered off any coagulum formed. The final non-neutralized latex has a solid component of 45.5%, an average particle size of 375 nm and a pH of 2.2.

Example  2: Polymer  Aqueous of particles Dispersion  formation

Using the same equipment as in Example 1, 1318.7 g of the first polymer together with 220 g of DI water of Example 1 were added to the bath tube and the temperature was adjusted to 25 ° C. Monomer emulsion (ME I) was prepared by mixing 306 g DI water, 17.0 g SDS, 416.4 g MMA, 12.0 g MAA and 591.6 g BA. At a bath temperature of 25 ° C., a solution of 20 g of 0.1% iron sulfate mixed with 2 g of 1% tetrasodium ethylenediamine tetraacetate, available from Versene ^™ (Dos Corp., Midland MI), was added to the bath tube. Next, a co-feed containing 1.2 g / t of a solution of 3.7 g of t-BHP (70%) mixed with 100.0 g of DI water with a separate solution of 2.6 g of iso-ascorbic acid mixed with 100.0 g of DI water. It was added to the teapot at the rate of minutes. Two minutes after the start of the cofeed solution, previously prepared ME I was added to the teapot at a rate of 15 g / min. No external heat was applied to the reaction. The temperature of the teapot was allowed to increase over the period of ME presentation. After 30 minutes, the ME I feed rate was increased to 30 g / min. At the completion of ME I, the co-feed was stopped and the reaction continued for 5 minutes. At this point, the temperature of the reaction was 78 ° C. Next, 400 g of hot DI water (90 DEG C) was added to the teapot. A second monomer emulsion (ME II) was prepared with 54 g DI water, 3.0 g SDS, 75.6 g MMA, 104.4 g BA and 2.5 g 4-hydroxy TEMPO (4-hydroxy 2,2,6,6- Tetramethyl piperidinyloxy radicals) were mixed and added to the teapot at a rate of 40 g / min until completion. Immediately after completion of ME II, 40 g ammonium hydroxide (28%) mixed with 40 g DI water was added to the kettle. The reaction lasted for 5 minutes. The cofeed solution was then restarted at a rate of 1.2 g / min until they were complete. The dispersion was then cooled to 25 ° C. and filtered to remove any precipitate. The filtered dispersion had a solid component of 45.5% and an average particle size of 480 nm. Kubelka-Munk scattering constants were measured on a dry polymer film and were observed at 40.6 S / μm (1.60 S / Mil).

Example  3: Polymer  Aqueous of particles Dispersion  formation

Using the same equipment as in Example 1, 1055 g of the first polymer of Example 1 together with 180 grams of DI water were added to the bath tube and the temperature was adjusted to 25 ° C. A monomer emulsion (ME I) was prepared by mixing 367 g DI water, 20.4 g SDS, 499.7 g MMA, 14.4 g MAA and 709.9 g BA. At a bath temperature of 25 ° C., a solution of 20 g of 0.1% iron sulfate mixed with 2 g of 1% Versene ^™ (Dos Corp.) was added to the bath. Next, 1.0 g / coupling, containing a separated solution of 3.2 g of iso-ascorbic acid mixed with 120.0 g DI water, and a 4.5 g solution of t-BHP (70%) mixed with 120.0 g DI water. It was added to the teapot at the rate of minutes. Two minutes after the start of the cofeed solution, previously prepared ME I was added to the teapot at a rate of 10.0 g / min. No external heat was applied to the reaction. The temperature of the teapot was allowed to increase beyond the period of ME presentation. After 30 minutes, the ME I feed rate was increased to 20 g / min. Co-feeding was stopped upon ME I completion and the reaction continued for 5 minutes. Next, 400 g of hot DI water (90 DEG C) was added to the teapot. A second monomer emulsion (ME II) was prepared by mixing 65 g DI water, 3.6 g SDS, 90.7 g MMA, 125.3 g BA and 3.0 g 4-hydroxy TEMPO, 40 g / min until completion It was added to the teapot at the rate of. Immediately after completion of the ME II feed, 48 g ammonium hydroxide (28%) mixed with 48 g DI water was added to the kettle. The reaction lasted for 5 minutes. Then the cofeed solution was restarted at a rate of 1.0 g / minute until they were completed. The dispersion was then cooled to 25 ° C. and filtered to remove any precipitate. The filtered dispersion had a 45.7% solids component and an average particle size of 540 nm. Kubelka-Munk scattering constants were measured on a dry polymer film and observed at 29.7 S / μm (1.17 S / Mil).

Example  4-13: Cardboard Coating

In the following examples, a cardboard coating was made and applied as an experimental drop using a wound rod. Examples 8 and 9 were applied to Omnova, Inc.'s Akron, OH pilot coater facility with conventional air knife coaters. The base used in the experimental drop was pre-coated recycled paperboard and / or pre-coated solid-unbleached sulfite (SUS) board.

In Examples 4, 5, 6 and 7, the coat weight was about 17.8-19.2 g / sq. Hand-dipped using Mayer wound rod # 12 (Buschman Corp (Cleveland, OH)) to be meters (12-13 lbs / 3300 square feet).

Construction attempts made for Examples 8 and 9 were carried out at 14 pt (0.03556 cm thick (0.014 inch)), (about) 222 g / m 2 (45.5 Ib / 1000 sq ft) or SUS (solid unbleached sulfite) base It was performed on board and coated at 364 m / min (1200 fpm) at 59 wt% solids for the base coat and 212 m / min (700 fpm) at 49 wt% solids for the top coat. Each roll was precoated with a standard base-coat formulation Gen FloTM 5128 SB styrene-butadiene latex binder (Omnova, Akron, OH) and topcoated with the coatings indicated in Table 1 below, followed by 364 m / min ( 1200 fpm), ambient temperature, separated calender at minimum calender pressure to maintain gloss lowered to a target range of about 45-50 units.

IGT dry peak experiments were performed using a 1 x 9 "[2.5 cm x 23 cm] strip of coated board samples coated with ink tags # 4 and # 5 with an A2 tester (IGT / Reprotest, The Netherland) on calendared cardboard samples. All hand-lowering coatings were calendered at 54.4 ° C. (130 ° F.), 206.8 kN / m 2 (30 psi), and 182 m / min (600 ft / min). 37.7 TO 41.6 ° C. (100-107 ° F.), 124-193 kN / m 2 (18-28 psi) and 162-198 m / min (530-650 ft / min) were calendared on the calendar of the experiment.

Table 1- Coating

Example 4 5 6 7 8 9 Hollow core binder none none Example 2 Example 3 none Example 2 Parts by weight Parts by weight Parts by weight Parts by weight Parts by weight Parts by weight Kaolin ¹ Clay 65 73 73 73 67 77 TiO ₂ 35 27 27 27 33 23 Hollow core binder 10 10 7 Vinyl Acetate-acrylate binder ² 20 20 10 10 Styrene-butadiene binder ³ 14 10 Alkali Swellable Acrylic Emulsion Seekner ⁴ 0.2 0.2 0.1 0.1 Soy Protein Binder ⁵ 3.5 3.5 3.5 3.5 3.5 3.5 Coating solids (%) 48 48 48 48 48 48

1. Hydrafine ^™ No. 1, JM Huber, Edison, NJ;

2. POLYCO ^™ P-3103NP binder, Rohm and Haas Company, Philadelphia, PA;

3. Gen Flo ^™ 5128, Omnova, Akron, OH;

4. ACRYSOL ^™ Ase-75 Seechner, Rohm and Haas Company, Philadelphia, PA; And

Procote 400, DuPont, Wilington, DE.

Table 2-Coating Properties

Example Sheet polished brightness PPS Smoothness IGT peak number Average Standard Deviation Average Standard Deviation Average Standard Deviation Average Standard Deviation 4 56.3 0.9 81.6 0.43 1.6 0.1 219 9 5 55.4 1.1 79.5 0.46 1.6 0.1 251 21 6 57.1 1.1 81.5 0.41 1.5 0.1 272 30 7 57.3 0.7 80.7 0.40 1.5 0.1 296 24 8 47.0 1.2 85.1 0.2 2.0 0.1 100 6 9 45.5 0.8 84.6 0.1 2.0 0.2 100 0

As shown in Examples 6 and 7, coatings made with the hollow core binder of the present invention provide coating properties equivalent or better than those of Examples 4 and 5, where Examples 4 and 5 have twice the binder In the case of Example 4, it further has 30% titanium oxide. As shown in Example 9, the coating made of the hollow core binder of the present invention is equivalent to or better than the coating of Example 8 having 40% binder and 42% titanium dioxide.

Table 3- Coating

Example 10 11 12 13 Hollow core binder compare compare Example 2 Example 3 Parts by weight Parts by weight Parts by weight Parts by weight Kaolin Clay 75 83 83 83 TiO ₂ 25 17 17 17 Hollow core binder 0 0 10 10 Vinyl Acetate-acrylate binder ² 20 20 10 10 Alkali Swellable Acrylic Emulsion Seekner ³ 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2 Soy Protein Binders ⁴ 3.5 3.5 3.5 3.5 Coating solids (%) 48 48 48 48

1. Hydrafine ^™ No. 1, JM Huber, Edison, NJ;

2. POLYCO ^™ P-3103NP binder, Rohm and Haas Company, Philadelphia, PA;

3. Gen Flo ^™ 5128, Omnova, Akron, OH;

4. ACRYSOL ^™ Ase-75 Seechner, Rohm and Haas Company, Philadelphia, PA; And

Procote 400, DuPont, Wilington, DE.

Table 4- Post-Calendar Coating Properties

Example Sheet polished brightness PPS Smoothness IGT peak number Average Standard Deviation Average Standard Deviation Average Standard Deviation Average Standard Deviation 10 54.9 1.2 79.1 0.4 1.5 0.1 221 32 11 53.9 1.1 77.1 0.4 1.5 0.1 229 16 12 53.9 1.5 79.2 0.4 1.5 0.1 291 11 13 54.8 1.1 78.2 0.4 1.5 0.1 307 7

As shown in Examples 12 and 13, a coating made of the hollow core binder of the present invention provides coating properties equivalent to or better than those of Examples 10 and 11, where Examples 10 and 11 have twice the binder In the case of Example 10, it further has 40% titanium oxide.

Claims (10)

At least one hollow-core binder of a first polymer containing at least one void, wherein the first polymer is substantially encapsulated by a second polymer, wherein one or both of the first polymer and the second polymer A polymerized unit, formed from one or more ethylenically unsaturated monomers, wherein the second polymer has a glass transition temperature (T _g ) in a range of greater than −15 ° C. and up to 30 ° C., wherein the second polymer to the first polymer Cardboard products having a coating thereon having a weight ratio of 1 to 4: 1 in the range At least one layer of paper laminate comprises cellulose fiber pulp, fillers and at least one hollow-core binder, said hollow-core binder comprising a first polymer containing at least one void, wherein the first polymer is incorporated into the second polymer. Substantially encapsulated therein, wherein one or both of the first polymer and the second polymer are formed as polymerized units, from one or more ethylenically unsaturated monomers, wherein the second polymer is greater than −15 ° C. and up to 30 ° C. Paper or paper laminate having a glass transition temperature (T _g ) in the range included, wherein the weight ratio of the second polymer to the first polymer is in the range of 1: 1 to 4: 1. The coated cardboard of claim 1 wherein the second polymer of the hollow core binder is formed from butyl acrylate, ethyl acrylate, ethyl hexyl acrylate and mixtures thereof as polymerized units. 3. The papermaking or papermaking laminate of claim 2 wherein the second polymer of the hollow core binder is formed from butyl acrylate, ethyl acrylate, ethyl hexyl acrylate and mixtures thereof as polymerized units. The void-containing core layer of claim 1, wherein the T _g of the first polymer is at least 50 ° C. and the first polymer of the hollow core binder comprises a multilayer polymer formed from at least one ethylenically unsaturated monomer as a polymer unit. Having coated cardboard. The method of claim 2 wherein the T _g of the first polymer is at least 50 ° C. and the first polymer of the hollow core binder comprises a multilayered polymer formed from at least one ethylenically unsaturated monomer as polymerized units, wherein the void-containing core layer is formed. Paper making or paper lamination. An aqueous dispersion of one or more hollow-core binders of the first polymer containing one or more voids, the first polymer being substantially encapsulated by the second polymer, wherein the first polymer and the second polymer One or both are polymerized units, formed from one or more ethylenically unsaturated monomers, and wherein the second polymer has a glass transition temperature (T _g ) in the range of greater than -15 ° C up to 30 ° C. Applying a coating composition having a weight ratio of the first polymer in the range of 1: 1 to 4: 1 to the cardboard substrate; A method of making coated cardboard comprising drying and / or curing to form a coating. 8. The method of claim 7, wherein the coating composition further comprises one or more binder polymers, one or more opaque pigments, or mixtures thereof. 8. The method of claim 7, wherein the weight ratio of the second polymer to the first polymer in the hollow core binder is from 2: 1 to 3: 1. The hollow core binder comprises a hollow-core of a first polymer containing one or more voids, the first polymer being substantially encapsulated by the second polymer, wherein one or both of the first polymer and the second polymer Is a polymerized unit, formed from one or more ethylenically unsaturated monomers, wherein the second polymer has a glass transition temperature (T _g ) in a range of greater than -15 ° C up to and including 30 ° C, wherein the second polymer to the first The aqueous dispersion of the at least one hollow core binder and the cellulose fiber pulp, wherein the weight ratio of the polymer is in the range of 1: 1 to 4: 1, is bonded before or during the formation of the sheet or board of the fiber pulp, Calendaring or pressing to form a sheet or board, but for paper laminates calendaring or pressing comprises calendering the sheet or board with one or more additional sheets or boards comprising wet fiber pulp to form a paper laminate and, A method of making a paper or cardboard product or paper laminate, comprising drying to form the paper or cardboard product or paper laminate.